In the drive technology there are many examples in which for operational reasons the working machine require the change-over of rotational direction of electric motors. In order to prevent an accidental or unintentional change-over of the set rotational direction of a drive motor, it is necessary to provide safety means in the form of key switches and visual displays.
Technically, the change-over switching of electric motors is achieved with conventional motor reversing contactors that can be electrically and/or mechanically locked relative to one another as is, for example, known from German Patent 38 23 574. The switching for the change-over of the rotational direction with respect to technical aspects is satisfactory and also easy to operate; however, this approach requires high expenditures and, in general, is not an economic solution.
One field of application for change-over switching is, for example, spinning and twisting machines, especially two-for-one twisting machines. As a function of whether a so-called S or Z twisted yarn is to be produced, the rotational direction of the spindles must be reversed. In most cases the drive of spinning or twisting machines is achieved with one or more interconnected electric motors whereby the torque is, in general, transmitted with a tangential drive belt to the individual working locations, i.e., the spindles.
It is therefor an object of the present invention to provide a simple and reliable device for change-over switching of individual electric motors or groups of electric motors, especially for spinning or twisting machines, with which the aforementioned components such as key switches, visual indicators, and reversing contactors are obsolete.